There are known from the prior art watches or timepieces whose timepiece module can indicate the date, i.e. the day of the month, and can also indicate the month.
For the most common watches, the date indication is not optimum since it does not take account of the different number of days in each month of the year. Consequently, in the months of thirty days, the date has to be adjusted to advance the date by two notches, whereas in February, the date has to be advanced at least four or even five notches in the case of a leap year, to obtain the correct date.
Perpetual calendar modules have been created to overcome this problem. These timepiece modules propose to indicate the date while taking account of the different numbers of days in each month of the year depending on whether the year is an ordinary or leap year. Consequently, this timepiece module can change from one month to another without intervention by the user.
However, one drawback of these perpetual calendar modules is that they require a prior setting operation. The prior setting operation may take place during manufacture or on the first use or on each battery change. The setting operation consists in entering a setting mode and then setting the various parameters. These parameters are the date, the month and the year, i.e. the current level in the four-year cycle. This adjustment is far from straightforward, since it is not easy for the user or the watchmaker to define the current level in the cycle: is it currently a leap year or the year before or after a leap year This question is more complicated than expected and if, in addition, the setting steps are not clear, it soon becomes a chore for the user to set the perpetual calendar.
Further, this drawback is accentuated if, when the perpetual calendar is being set, there is no indication displayed as to what it is the user is setting. Indeed, if he does not know whether he is setting the day, the month or the year, the user is likely to give up.